KEYNOTE Biogeochemistry of trace elements in wetland soils

Wetlands, especially floodplains, offer a variety of ecosystem functions. One of the most important is their ability to act as a water regulator. Floodplains also fulfil important retention functions in relation to the... [ view full abstract ]

Wetlands, especially floodplains, offer a variety of ecosystem functions. One of the most important is their ability to act as a water regulator. Floodplains also fulfil important retention functions in relation to the cycling and treatment of nutrients and contaminants. Therefore, contamination of wetland soils by potentially toxic elements (PTEs) is of serious environmental concern. Many floodplain soils world-wide are polluted what can increase the solubility and leaching of PTEs resulting in adverse impacts on the agricultural environment. The PTEs can be released from soil to soil solution, particularly under different flood-dry-cycles, and can be transferred through the food chain, thus posing a hazard to environmental and human health. Therefore, the release kinetics of PTEs including their controlling factors are highly relevant because they affect both scientific and practical issues regarding protection of groundwater and plants, sustainable management of soils, and our understanding of environmental pathways taken by harmful substances. At the same time, it is scientifically challenging to elucidate the underlying biogeochemical processes and drivers that control the dynamics of PTEs due to the high natural complexity of these ecosystems which have a unique oxic and anoxic soil environment. The redox potential (EH), and pH are master variables in controlling the release of dissolved PTEs, however, the mobilization of PTEs is a complex process and govern by many factors such as the chemistry of iron, manganese, sulfur, chloride, aliphatic and aromatic dissolved organic carbon, and microorganisms. This presentation provides an overview about the recent knowledge to the topic.